Estimated economic impacts of the US Green Industry are 1,964,339 jobs, and $147.8 billion in output, of which 27% is represented by the greenhouse and nursery sector. Little research has been conducted so far in the United States on the exposure to respiratory sensitizer bioaerosols in greenhouses and their association with allergic rhinitis, occupational asthma, and other respiratory health problems of the workers. The goal of this study is to collect pilot data for an ensuing R01 proposal addressing exposure risks to respiratory health hazards, prevalence of respiratory symptoms among the Green Industry workers, and exploring intervention methods at the same time considering the possible protective effect of endotoxin and (1?3)-[unreadable]-D-glucan exposures against allergen sensitizations. Workers'exposures to airborne pollen, molds, bacteria, actinomycete, endotoxin, and (1?3)-[unreadable]-D-glucans in three Midwest greenhouses will be investigated during spring and winter and the concentrations will be compared with reported levels in the greenhouses of other countries, other agricultural workplaces, and nearby ambient air. The work-shift average and task-specific exposures to bioaerosols will be studied by using inhalable samplers during different work tasks. To understand the sources of bioaerosols, surface sampling of biological particles on the floors and hard surfaces will be performed. Moreover, potential source strengths of these surfaces for aerosolizing biological particles will be determined by Fungal Spore Source Strength Tester developed by our research group. Environmental parameters including temperature, relative humidity, and wind velocity will be measured during each air sampling experiment. The correlation between different environmental variables and bioaerosol exposure levels will be determined. To understand the prevalence of rhinitis, wheezing, respiratory allergies, asthma, and other respiratory symptoms among the greenhouse workers and its association with different greenhouse work tasks and bioaerosol levels, a preliminary questionnaire survey will be conducted involving 45 workers and 15 control subjects from three greenhouses. The proposed project is relevant for the NORA2's 'Agriculture, forestry, and fishing'sector group, three cross-sector programs (Health hazard evaluation, Respiratory diseases, and Communications and information dissemination) and two coordinated emphasis areas.